U.S. President Barack Obama has said the United States and its Gulf allies have pledged to continue working together to fight the extremist group Islamic State (IS) and de-escalate other regional conflicts.

Obama, in remarks following the U.S.-Gulf Cooperation Council summit in the Saudi capital Riyadh, said concerns remain over economic issues, including oil, and the behavior of Iran in the region.

But Obama said: "None of our nations have an interest in conflict with Iran."

Washington's Gulf allies have been wary of the nuclear deal with their regional rival, Tehran.

Obama said the six-nation Gulf Cooperation Council had agreed to enhance humanitarian efforts in Iraq and Syria and remains united in its efforts to destroy IS.

He said there had been progress in the fight against the militant group, which has lost territory in Iraq and Syria in recent months.